This invention relates generally to an apparatus for hitching a towed vehicle to a towing vehicle and more particularly to an improved hitch apparatus for a multi-axle trailer with automotive type spindle steering.
Towed vehicles in general may be classified according to whether they have a solid mounted hitch or a pivotally mounted hitch for steering front wheels of the towed vehicle. The first type would include single axle double wheel trailers such as small boat trailers and larger multi-axle vehicles wherein the axles are closely spaced such as a multi-axle mobile home or heavy-duty gravel trailer. The second type of towed vehicle includes those with spaced-apart front and rear wheels wherein the front wheels are supported for automotive type spindle steering. Most farm wagons are of this type. Such vehicles include a tongue pivotally connected to the vehicle frame and pivotally connected by tie rods to the front wheels for steering the front wheels in response to lateral pivotal movement of the tongue.
Vehicles of the second type are advantageous in that they are self-supporting independently of the towing vehicle. The disadvantage is that they are much more difficult to handle when backing up because of the double pivotal connection between the towing vehicle and towed vehicle at opposite ends of the tongue.
Another problem associated with towed vehicles of the second type is that of alleviating some of the load on the steerable front wheels of the vehicle. Heavy-duty vehicles such as large forage wagons may be provided with double rear axles for distributing the weight at the rear of the wagon onto more wheels. But because the front wheels are steerable, it would be impractical to provide double front wheels supported one behind the other.
Prior apparatus have been developed in an attempt to make a steerable towed vehicle respond like a single axle two-wheel trailer but these have had several problems associated with them. See for example Watson U.S. Pat. No. 3,876,240 wherein a two ball hitch to a towing vehicle is disclosed. This arrangement requires precise alignment between the towing vehicle and trailer or the connection cannot be made. Another problem associated with such apparatus is that up and down pivotal movement of the tongue tends to induce steering movement of the steerable trailer wheels.